I have tried to make some self-watering plant boxes where I 3D-print some containers with holes to act as wicks to absorb moisture into a top container with soil. The wicks themselves are packed with soil.

However, some white mold quickly builds up around some of the holes (fairly self-limiting though, it does not get much more than what you see in the attached picture after some days since I first noticed it). I emptied the water and re-cleaned the box, and wiped off the wicks. The existing water had a slight sewage smell to it.

For now, the boxes are directly exposed to light, but will be built in by a wooden enclosure in the "final product".

1. Should this be of any concern for the plants growing in the soil? They will be edible greens.
2. Can I avoid this, while still using my 3D-printed parts?